Many attempts have been made to produce 3-D motion pictures. The technique generally used involves simultaneously photographing a subject using two motion picture cameras positioned to provide "left eye" and "right eye" views of the subject. The images recorded on films in those cameras are then simultaneously projected onto a screen and are optically coded in some way so that the left eye of a viewer sees only the images that were recorded by the "left eye" camera while the viewer's right eye sees only the "right eye" images. The viewer then perceives a stereoscopic or 3-D effect.
One method of coding the images involves using colour filters (anaglypta). For example, the right eye images may be coloured blue and the left eye images red and the viewer provided with spectacles having filters that are coloured so that the viewer's right eye sees only blue images and the left eye sees only red images. A disadvantage of this technique is of course it can be used only with two monochrome images and produces a monochrome 3-D image. A related technique that can be used with full colour motion pictures involves the use of polarized light. By providing the respective left and right eye projectors with filters that are polarized in directions at 90.degree. to one another and providing the viewer with spectacles having correspondingly polarized lenses, full colour 3-D images can be viewed.
Spectacular 3-D motion pictures can be made by using these known techniques with large format films such as those that are available from Imax Systems Corporation of Toronto, Canada under the registered trade marks IMAX and OMNIMAX. The use of large format films has become possible as a result of development of the so-called "rolling loop" film transport mechanism for cameras and projectors. U.S. Pat. No. 3,494,524 to Jones discloses the principle of a rolling loop transport mechanism. A number of improvements in the original Jones mechanism are disclosed in U.S. Pat. Nos. 3,600,073, 4,365,877 and 4,441,796 (all to Shaw).
A practical difficulty of making 3-D motion picture films is that presently available cameras cannot be positioned sufficiently close to one another that the axes of the camera lenses are at the required interocular distance of two to three inches (i.e. a typical eye spacing) that is necessary to obtain a proper 3-D effect. Attempts to achieve interocular spacing by interposing prisms, mirrors or other optical devices between the cameras and the subject to be photographed result in image reversals that must be compensated for example by special optical printing steps or by mirrors in the projector optics.
Examples of prior art publications in this area are:
British Patent No. 740,927 (Spottiswoode et al.) PA0 Letter from Polaroid Corporation, dated Aug. 9, 1956 signed by Donald L. Brown (copy in U.S. Pat. Classification No. 352-59) PA0 "3-D IMAX Camera Assembly", Perforations, Vol. 4, No. 4, 1984. PA0 "3-D IMAX Progress Report", Perforations, Vol. 4, No. 4, 1984. PA0 "Future Cinema", Perforations, Vol. 4, No. 3, 1984. PA0 "Large Screen 3-D--Aesthetic and Technical Considerations", Perforations, Vol. 3, No. 4, July 1983.
An object of the present invention is to provide an improved method of producing and displaying 3-D motion pictures which permits interocular spacing to be achieved when the motion picture is being made, while avoiding the need for special optical printing steps or modification of projector optics. A further object is to provide a camera for use in the method.